1. Field of the invention
This invention relates to a method of manufacturing a near field light generation element which generates a near field light.
2. Description of the Related Art
The near field light generation element is used in an optical head in an optical storage device performing a high density information record/regeneration, an optical probe in a near field light microscope performing an observation under a high resolution, and the like. Since a near field light technique can treat an optical information of a minute region exceeding a diffraction limit of light, it is expected that there are obtained a high recording density and a high resolving power, which are not capable of being attained by a conventional, optical technique.
In the near field light generation element, it is a main problem to obtain a spot of the near field light which is minute and strong. For that purpose, several forms are already proposed. In Patent Document 1, by making a contour shape of an optical aperture having been provided in a tip of the near field light generation element into a triangle and by being made a structure in which a polarization direction of an incident light and one side of the triangle intersect perpendicularly, there is generated the strong near field light having been localized to that one side (triangle aperture system). In Non-Patent Document 1 and Patent Document 2, metal films are formed on two opposite faces among four side faces of a quadrangular pyramid, these two faces have a gap, which is the same as or smaller than a wavelength of the light, in the vicinity of an apex of the quadrangular pyramid, each of the metal films on the two faces has respectively in its gap part an apex whose radius of curvature is several tens nm or less, and there is generated the strong near field light having been localized to the gap part (bow tie antenna system).
[Patent Document 1] JP-A-2001-118543
[Patent Document 2] JP-A-2002-221478
[Non-Patent Document 1] Technical Digest of 6th international conference on near field optics and related techniques, the Netherlands, Aug. 27-31, 2000, p100
Among the prior arts mentioned above, about the near field light generation element of the triangle aperture system of the Patent Document 1, there is already disclosed a manufacturing method, and it can be comparatively, easily manufactured. However, about the near field light generation element of the bow tie antenna system of the Non-Patent Document 1 and the Patent Document 2, from the fact that a working of several nm to several tens nm is required in shapes of the metal film apex and the gap part, generally it has been necessary to use a highly advanced micro-fabrication technique such as electron beam lithography apparatus or focused ion beam apparatus. In regard to this, there is demanded a manufacturing method which is simple and suitable for mass production.